Studies On Oral Colon-specific Capsules Of Panax Notoginseng Saponins Liposomes

Panax notoginseng saponins(PNS) is the extraction of the total saponins from the roots and rhizomes of Panax Notoginseng(Burk.) F. H. Chen, a traditional Chinese medicine, which is the main component of Xuesetong, Xueshuantong and other Chinese patent medicines. PNS has specific clinical curative effects of reducing myocardial oxygen consumption and improving myocardial blood supply, is considered to be the material basis for the treatment of circulatory disorders and cardiovascular disease. However, PNS decomposed easily in the environment of gastric acid, and the intestinal mucosal permeability of its is low, leading to its low oral bioavailability and limited clinical applications. At present, the study of PNS oral small enteric preparations can solve the stability problem. However, small intestine has powerful digestion and absorbtion capacity and short residence time. Patients who suffer from chronic diseases such as cardiovascular or cerebrovascular diseases need to take the medication frequently, which is very inconvenience.Oral colon-specific drug delivery system(OCDDS) was created initially for the preparation of drugs for local lesions in colon. However, with the deepening of study, colon is considered to be a promising drug absorption site for treatment of various diseases, and colon-specific preparations are also applied to develop different types of drugs. Meanwhile liposomes have a good biocompatibility due to its special lipid bilayer structure. Liposomes can increase the permeability of drugs, thereby enhancing the absorption of drugs in colon.Objective: Study and preparation of quality stable and controllable oral colon-specific capsules of PNS liposomes, and explore the new way of the drug delivery into body by oral colon specific preparation.Methods:(1) Establish a high-performance liquid chromatography(HPLC) method for simultaneous determination of notoginseng R1 and ginsenosides Rb1, Rg1, Rd and Re.Analyze the main physical and chemical properties(including stereochemistry, intrinsic solubility, partition coefficient, the number of intramolecular hydrogen bond donor and acceptor) of the five saponins of PNS by Marvin sketch softeware.(2) Thin film hydration method was selected to prepare the PNS-loaded liposomes. Based on the results of single factor experiments, Box-Behnken design was used to obtain the optimal liposome formulation. The optimal formulation was validated and evaluated, and the stability of the liposomes was studied.(3) Study the absorption condition of PNS-loaded liposomes in colon using rat single-pass intestinal perfusion method. Compare the drug absorption rate constant(Ka) and apparent absorption coefficient(Papp) between PNS solution and PNS loaded liposomes.(4) PC-12 cells were cultured and the oxidation stress model was established to study the efficacy of PNS liposomes in vitro. MTT assay was used to detect cell viability rate after treatment with H2O2.(5) The pH-sensitive colon specific capsule shells were preparated by dipping method, and the freeze dried liposomes were encapsuled into the shells. Releasing characteristic of the capsules was studied in gastrointestinal-simulated p H buffers.Results:(1) Egg lecithin was selected as lipid material and the film hydration method was selected as the preparation method. The optimized ratio of drug or cholesterol to lipid was 23.57% and 13.68% respectively, and the drug concentration was 4.64 mg ? m L-1. By prescription verification, the system average liposome encapsulation efficiency was 82.9%, with an average of 14.7% drug loading, the average particle size was 183.0 ± 2.25 nm, Zeta potential was-12.8 ± 0.79 m V. Storage under 4 ℃ environment within 15 d shows good stability. PNS loaded liposomes incubated in rat colon contents solution show good stability within 8 h at 37 ℃, the amount of drug leakage was 6.6±0.41%.(2) In rat intestinal absorption experiments, within a certain range, the PNS absorptionrate constant and apparent absorption coefficient in colon are positive correlated with perfusion rate, while no significant correlation with drug concentration. The absorption rate constant and apparent absorption coefficients of PNS-loaded liposomes were significantly higher than that of PNS solution in colon area.(3) In vitro cell experiments, compared with the PNS solution, physical mixtures and blank liposomes, PNS liposomes have a more significant protective effect on H2O2 induced oxidative damage of PC-12 cells, and a more significant increase in cell survival rate.(4) The optimal formulation of colon specific capsule shells by dipping method was: Eudragit S100 1.0 g, PEG 6000 0.4 g, glycerol, 1.0 m L, acetone 10.0 m L; dipped in glue and repeat for 7 times, 40 ℃ dryness for 8 h. The in vitro release experiment results showed that the accumulation release rate of drug in the acid p H 6.8 buffer <10% of the total amount, the accumulative release in p H 7.8 buffer > 70% of the total amount within 1h, compliance with the requirements of Chinese Pharmacopoeia.Conclusion: Oral colon-specific capsule of Panax notoginseng saponins liposomes can specific release PNS liposomes in colon. The preparation can increase the absorption rate and the apparent absorption coefficient of PNS in colon. It can protect the PNS from been decomposed and improve its oral absorption rate in colon.